1. Field of the Invention
The present invention relates to a speed detecting device mounting structure for a vessel in which a speed detecting device is provided on a ship bottom plate to obtain a propelling speed of the vessel by detecting a flow rate of water by means of a paddle in the speed detecting device.
2. Description of Background Art
One of the existing types of jet propulsion boats includes a water jet pump mounted on a rear portion of the vessel body. The jet propulsion boat is propelled by sucking water from the ship bottom by driving the water jet pump and splashing or spraying the sucked water rearward. This type of jet propulsion boat is provided with a speed detecting device on the ship bottom plate at the rear portion of the vessel body for detecting the propelling speed.
For example, a speed detecting device mounting structure is disclosed in Japanese Patent Laid-Open No. 304831/11 entitled xe2x80x9cPROPELLING SPEED DETECTING DEVICE FOR VESSELS.xe2x80x9d This technology will be described below with reference to FIG. 6 of the present specification, which is a view similar to FIG. 5 of the above publication.
FIG. 6 is a bottom view of the rear portion of the vessel in the background art, showing a state in which a speed detecting device is mounted on the ship bottom plate. The vessel 100 includes a ship bottom plate 101 formed with a flowing water draining groove 102 extending in the fore-and-aft direction of the vessel. A notch 103 is formed at the rear end of the flowing water draining groove 102. A body of revolution (hereinafter referred to as a paddle) 106 of the speed detecting device 105 is rotatably mounted on the notch 103. Furthermore, a sensor body 108 for detecting the number of revolutions of the paddle 106 is provided in the vicinity of the paddle 106.
According to the above speed detecting device mounting structure, when the vessel 100 is propelled by a water jet pump (not shown), water runs along the flowing water draining groove 102 as shown by the arrow a. Water flowing in the direction of the arrow a reaches the paddle 106, strikes the blades 107 of the paddle 106, and rotates the paddle 106. The propelling speed of the vessel 100 can be obtained by detecting the number of revolutions of the paddle 106 by the sensor body 108.
However, the speed detecting device mounting structure is provided with the paddle 106 at the notch 103 of the ship bottom plate 101 in the background art. Accordingly, the paddle 106 is exposed to the sea via the notch 103. Therefore, the paddle 106 may be entangled with rubbish or seaweed drifting in the sea.
In addition, since the paddle 106 is exposed to the sea, if the vessel 100 runs ashore, the paddle 106 is in danger of contacting the sea bottom. Accordingly, the paddle 106 may be damaged or mud from the sea bottom may be picked-up by the paddle 106, affecting proper operation of the speed detecting device.
Accordingly, the object of the present invention is to provide a speed detecting device mounting structure for a vessel in which a paddle is prevented from being entangled with rubbish or seaweed in the sea, and from being damaged by the sea bottom or picking-up mud from the sea bottom.
In order to solve the problems described above, according to a first aspect of the present invention, a vessel comprises a water jet pump provided at a rear portion of the vessel, a ship bottom plate provided below the water jet pump, a speed detecting device mounted on the ship bottom plate, a paddle of the speed detecting device being rotated by water so as to obtain the propelling speed based on the rotation of the paddle, wherein the paddle is disposed above the ship bottom plate, an opening is formed at the portion of the ship bottom plate forwardly of the paddle, and water taken through the opening is guided to the paddle.
The paddle of the speed detecting device is disposed above the ship bottom plate and an opening is formed forwardly of the paddle. By covering the paddle with the ship bottom plate, the paddle can be closed off from the sea by the ship bottom plate. Therefore, the paddle can be protected by the ship bottom plate. Accordingly, the paddle can be prevented from being entangled with rubbish or seaweed drifting in the sea.
In addition, by protecting the paddle with the ship bottom plate, even if the vessel runs ashore, the paddle is prevented from being damaged or picking-up mud from the sea-bottom.
Further scope of applicability of the present invention will become apparent detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.